The present invention is directed to a method for covering at least one optical waveguide with a protective layer and for applying reinforcing elements. In particular, the invention is directed to a method for covering at least one optical waveguide with a protective covering which surrounds the optical waveguide on all sides and is applied by extrusion together with reinforcing elements embedded in the covering.
DE-OS 39 00 901 discloses a method in which reinforcing elements are extruded in the form of threads from individual nozzles of an extruder, which nozzles are arranged around the periphery of a circle surrounding a bore. An optical waveguide, which is provided with a coating, is fed through a bore of the extruder head. In a subsequent stranding process, the reinforcing threads are applied with alternate directions of lay to the coating of the optical waveguide. An additional coating is then applied by means of another extruder. The reinforcing thread, thus, lies in a closed layer below the outer jacket or protective coating, which surrounds the whole structure. There is not a particularly strong bond between the outer protective covering and the underlying reinforcing threads so that a substantially two-layer structure results wherein both layers are independent of each other. Another disadvantage of this known method is that the threads consisting of liquid crystal polymers (LCP) or similar tension-resistant materials must be applied in an individual stranding process to the relatively thin and, therefore, sensitive optical waveguide, which has only been provided with one coating layer.